<template>
    <div>
        <router-link tag="div" to="/" class="header-abs" v-show="showAbs">
            <div class="iconfont header-abs-back">&#xe624;</div>
        </router-link>
        <div class="header-fixed" v-show="!showAbs" :style="opacityStyle">
            <router-link to="/">
                <div class="iconfont header-fixed-back">&#xe624;</div>
            </router-link>
            景点详情
        </div>
    </div>
</template>
<script>
export default {
    name: 'DetailHeader',
    data () {
        return {
            showAbs: true,
            //渐隐效果
            opacityStyle: {
                opacity: 0
            }
        }
    },
    //写方法
   methods: {
        handleScroll () {
            //console.log('scroll')
            //页面的高度
            const top = document.documentElement.scrollTop
            if (top > 60) {
                let opacity = top / 140
                opacity = opacity >1 ? 1: opacity
                this.opacityStyle = { opacity }
                this.showAbs = false
            }else{
                this.showAbs = true
            }
            console.log(document.documentElement.scrollTop)
        },
   },
    //监听
    activated () {
        window.addEventListener('scroll',this.handleScroll)
    },
    //事件解绑
    deactivated () {
        window.removeEventListener('scroll',this.handleScroll)
    },
}
</script>
<style lang="stylus" scoped>
@import '~styles/varibles.styl'
    .header-abs{
        position: absolute
        left: .2rem
        top: .2rem
        width: .8rem
        height: .8rem
        line-height: .8rem
        border-radius: .4rem
        text-align: center
        background: rgba(0, 0, 0, .8)
    }
      .header-abs-back{
        color: #fff
        font-size: .4rem
      }
    .header-fixed{
        z-index: 2
        position: fixed
        top: 0
        left: 0
        right: 0
        height: $headerHeight
        line-height: $headerHeight
        text-align: center
        color: #fff
        background: $bgColor
        font-size: .32rem
    }
     .header-fixed-back{
        position: absolute
        top: 0
        left: 0
        width: .64rem
        text-align: center
        font-size: .4rem
        color: #fff
     }
</style>
